class Athlete:
    def __init__(self, name = "None", age = 0):
        self._name = name 
        self._age = age
    def how_big(self):
        return self._name + ": " + str(self._age) 

a = Athlete("Andy", 20)
print(a.how_big())

b = Athlete("Fancy")
print(b.how_big())